Cismaş T. et. al./Scientific Papers: Animal Science and Biotechnologies, 2012, 45 (2)
Studies on some factors influencing the shape of the lactation
curve in Romanian Black and White cows
Traian Cismaş, Ludovic-Toma Cziszter, Stelian Acatincăi, Simona Baul,
Silvia Erina, Dinu Gavojdian
Faculty of Animal Sciences and Biotechnologies Timişoara, 300645 - Timişoara, Calea Aradului, 119, Romania
Abstract
The aim of this paper was to study the effects of farm and parity on the shape of the lactation curve for milk yield,
milk fat percentage, milk protein percentage and milk lactose percentage. Researches were carried out on 421
lactations obtained from a population of 260 Romanian Black and White cows reared in the South-eastern Romania.
Test day data was modelled using the incomplete gamma function, and then the lactation curves were drawn taking
into consideration the effect of farm (farm 1 and farm 2) and parity (lactation 1, 2 and 3+). Both factors had a
significant effect (p<0.05) on the shape of the lactation curve, affecting the initial production (parameter a), the rate
of increase/decrease to the peak/nadir (parameter b), as well as the rate of decrease/increase of production until the
end of lactation (parameter c).
Keywords: cow, farm management, lactation curve, parity, Romanian Black and White.
1. Introduction
during lactation is lower than the variation of milk
yield [1]. From the chemical components of milk,
fat percentage has the highest variation during the
lactation, followed by protein, while lactose and
minerals ha the lowest variation.
The shape of the lactation curve was studied on
Red Holstein x Romanian Spotted crossbred cows
on 212 lactations [4]. It was concluded that up to
25% Red Holstein genes in cows’ genotype did
not affected significantly the shape of the lactation
curve, but the daily milk production was 15%
higher. The shape of the lactation curve depends
on the milk secretion rate during lactation, which
is dependent of the body condition of animals at
calving, feeding level and available feedstuff, as
well as of the environmental conditions during
lactation [5]
If the genetic aspects that had an influence on the
shape of the lactation curve could be precisely
determined, then a mathematic model could be
elaborated in order to assist in cows selection,
improving thus the economic efficiency in cow
milk production [6].
Milk production evolution during lactation could
be presented graphically as the lactation curve.
This curve has three phases: ascendant, plateau
and descendant [1,2].
The shape of the lactation curve is a breed
characteristic, though it is hard to establish the
lactation curve characteristic with high precision for
each cattle breed because the milk yield and
composition are influenced by a large number of
genetic (breed, individual etc.), physiological (parity,
age at first calving etc.) and management factors, of
which a great influence has the feeding [3].
The range that chemical components of milk vary
during lactation is different from one breed to
another. In most breeds the fat percentage range
from 3 to 5%, protein percentage from 2.5 to 4%,
lactose percentage from 4.5 to 5% and the
minerals percentage from 0.65 to 0.8%. Generally,
the variation of chemical components of the milk

* Corresponding author: Traian Cismaş, Tel , Fax,
Email: traian.cismas@yahoo.com
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Cismaş T. et. al./Scientific Papers: Animal Sciences and Biotechnologies, 2012, 45 (2)
Many scientists that studied the shape of the
lactation curve had come to the same conclusion
that this was flatter in the first lactation than in
later lactations (5,7-9,10-12). This means that
lactation persistency, milk increase and decrease
rates before and after reaching the peak production
where higher and milk production at peak was
lower in primiparous cows compared to
multiparous cows. Also, cows in first lactation had
longer ascendant phase compared to multiparous
cows. All these aspects demonstrate that the
secretory tissue of the mammary gland in
primiparous cows need a longer time to reach the
maximum activity compared to multiparous cows.
A strong interaction between parity and the
average milk production of the farm was observed
on the shape of the lactation curve (13,14).
The aim of this paper was to study the effect of
farm management and parity on the shape of the
lactation curve for milk yield and chemical
composition in Romanian Black and White cows.
These averages were used to calculate the
parameters of the lactation curves by using the
gamma incomplete function [16].
yn = anbe-cn
where: e is the base of the natural logarithm; yn is
the milk yield or fat, protein and lactose
percentage at the n days from calving; a is the
initial level of production; b is the
increasing/decreasing rate of production until de
peak/nadir; c id the decreasing/increasing rate of
production after the peak/nadir.
Peak/nadir production is calculated as ymax =
a(b/c)be-b, and the days from calving when this
production is reached is calculated as n = b/c.
Using these parameters, the lactation curves were
drawn and presented in graphs according to the
two factors studied.
3. Results and discussion
Figure 1 presents the lactation curve for milk yield
in the two studied farms. The level of the milk
yield was significantly higher (p<0.001) in F2
than in F1. Thus, the parameter a was higher in F2
than in F1 (17.4 kg vs. 10.4 kg).
The shape of the lactation curve for milk yield was
different in F1 compared to F2. Thus, in F1 the
daily milk yield increased more rapidly (b =
0.12672) up the peak yield of 17.7 kg at 184 days
in milk and decreased slower thereafter (c =
0.00069) compared to F2 where milk yield
increased slower (b = 0.08988) and for shorter
time (77 days) until the peak of 23.6 kg, then
decrease more rapidly (c = 0.00117). Thus cows in
F2 had sharper lactation curves than cows in F1,
being more difficult to manage from the nutrition
point of view.
The lactation curves for fat percentage in the two
farms are shown in Figure 2. In F1 the initial level
of fat percentage (a) was significantly higher than
in F2 (4.5% vs. 3.5%, p<0.001). Fat percentage
decrease (b) until the nadir was higher in F1 than
in F2 (-0.034076 vs. -0.011118), the nadir point
was reached later in lactation (140 vs. 36 days),
the fat percentage at nadir was higher (3.9% vs.
3.4) and then the increase rate (c) was slower (0.000244 vs. -0.000308). These characteristics
made the shape of the lactation curve to look
flatter in F2 than in F1.
2. Materials and methods
Researches were carried out on 260 Romanian
Black and White cows of Holstein-Friesian type
reared in two dairy farms from Brăila County,
South-eastern Romania. Cows calved from
January 2009 until December 2010. Thus, a
number of 421 lactations were obtained from the
260 cows. Only those lactations were considered
that ended until December 31, 2010 and had at
least 11 controls.
Periodical controls were carried out using the
official technique [15] with the period of 28 days
and the control day in the middle of the period.
Milk yield was measured in kilograms by using
ICAR approved milkmeters and a total of 9262
milk samples were analysed for fat, protein, and
lactose percentage using the in-line devices built
in the milking equipment. Data was collected
using special designed software built in the
milking equipment.
The resulting database was used to calculate the
averages for each studied effect: farm with two
levels farm 1 (F1, n=128) and farm 2 (F2, n=293),
and parity with three levels first lactation (n=87),
second lactation (n=84) and third and over third
lactation (n=250).
295
Milk yield (kg)
Cismaş T. et. al./Scientific Papers: Animal Sciences and Biotechnologies, 2012, 45 (2)
25
23
21
19
17
15
13
11
9
7
5
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Farm 1
Farm 2
Figure 1. The shape of the lactation curve for milk yield according to the farm
management in Romanian Black and White cows
Fat percentage (%)
5
4,5
4
3,5
3
2,5
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Farm 1
Farm 2
Figure 2. The shape of the lactation curve for fat percentage according to the farm
management in Romanian Black and White cows
Figure 3 shows the lactation curve for protein
percentage according to the farm. Again, there
was a great difference between the two farms
regarding the shape of the lactation curve for
protein percentage. The initial protein percentage
was higher in F2 than in F1 (4.6 vs. 3.78%,
p<0.001), but also, the F2 cows had a steeper
lactation curve for protein than cows in F1. In F2
the decreasing rate of the protein percentage to
nadir, as well as the increasing rate afterwards was
higher than in F1 (-0.087727 and -0.000602 vs. 0.012979 and -0.000124, respectively). Even
though the initial protein percentage was higher in
F2 than in F1, the nadir value was lower, and was
reached later in lactation (3.3% and 146 days vs.
3.6% and 104 days, respectively).
All these characteristics resulted in flatter lactation
curve for protein percentage in F1 than in F2.
The two lactation curves for lactose percentage in
milk corresponding to the two studied farms are
presented in Figure 4. The two lactation curves
had a similar shape, but the initial starting level
were different, in F1 the initial lactose percentage
was 4.6%, while in F2 it was close to 5%. After
that the lactose percentage slightly increased
reaching a peak percentage of 4.8% at the end of
the normal lactation in F1 and 5.2% at 139 days in
milk in F2.
Figures 5 to 8 show the lactation curves for milk
production and chemical composition according to
the parity of cows.
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Cismaş T. et. al./Scientific Papers: Animal Sciences and Biotechnologies, 2012, 45 (2)
Protein percentage (%)
The initial milk yield was similar for cows in first
and third and over third lactation (16.8 and 16.6
kg, respectively), but was significantly lower for
cows in the second lactation (11.4 kg, Figure 5).
5
4,5
4
3,5
3
2,5
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Farm 1
Farm 2
Figure 3. The shape of the lactation curve for protein percentage according to the farm
management in Romanian Black and White cows
Lactose percentage (%)
5,3
5,2
5,1
5
4,9
4,8
4,7
4,6
4,5
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Farm 1
Farm 2
Figure 4. The shape of the lactation curve for lactose percentage according to the farm
management in Romanian Black and White cows
The parity significantly affected the lactation
curve parameters (b and c) for milk yield,
resulting in different shapes of the curves. Thus,
the flattest curve was observed in the first
lactation that started at a high level (16.8 kg), has
a very slow increase (0.02318) to the peak, which
was not very high (18.5 kg) and was reached late
in lactation (175 days in milk) , then the milk yield
decreased very slow (0.00013) until the end of
lactation. On the opposite, the second lactation
cows showed a very low initial milk yield (11.4
kg), with a very high rate of increase (0.15867)
until the peak production, which was almost
double than the initial production (20.6 kg) and
was achieved after the first third of lactation (115
days in milk), then the decrease was also abrupt
(0.00138).The most typical lactation curve showed
the cows in the third or over third lactation. These
cows started the lactation a high level (16.6 kg),
with a moderate rate of increase (0.09723) up to
the peak production that was reached very early
(82 days in milk) at a high level (23.1 kg), the
followed by a moderate rate of decrease of daily
production (0.00118).
The lactation curves for fat percentage in milk
according to the parity are presented in Figure 6.
Again, the shapes of the first lactation and third
and over third lactation were similar, the only
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Cismaş T. et. al./Scientific Papers: Animal Sciences and Biotechnologies, 2012, 45 (2)
Milk yield (kg)
difference being the staring level, 3.5% in first
lactation and 3.9% in third lactation. The
parameters of the curve were similar, b parameter
was -0.15181 for lactation 1 and -0.012929 for
lactation 3+, and c parameter was -0.000425 and 0.000398, respectively. The nadir point was 3.4%
for lactation 1 and 3.7% for lactation 3+, which
was reached very early in lactation for both
classes (36 and 32 days in milk, respectively).
The second lactation cows showed an atypical
shape for fat percentage, the initial level being
also the highest with a very low inflection of the
curve throughout the lactation. This resulted into
an almost linear increase of the fat percentage
from the beginning to the end of lactation.
25
23
21
19
17
15
13
11
9
7
5
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Lactation 1
Lactation 2
Lactation 3+
Fat percentage (%)
Figure 5. The shape of the lactation curve for milk yield according to the parity
in Romanian Black and White cows
4,4
4,2
4
3,8
3,6
3,4
3,2
3
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Lactation 1
Lactation 2
Lactation 3+
Figure 6. The shape of the lactation curve for fat percentage according to the parity
in Romanian Black and White cows
Lactation curves for protein percentage in milk of
the cows according to parity are presented in
Figure 7. There was observed a similar shape of
the lactation curve for protein percentage between
lactation 2 and lactation 3+. They both started at
the same level, 4.7% in lactation 2 and 4.5% in
lactation 3+, they have similar decreasing rate
until the nadir percentage (-0.090620 and 0.077678, respectively), and a similar increasing
rate thereafter (-0.000404 and 0.000516,
respectively), a very close nadir value (3.2% and
3.3%, respectively), which was reached later by
cows in lactation 2 (224 days in milk) than cows
in lactation 3+ (150 days in milk).
The curve for protein percentage in first lactation
cows was somehow atypical and very flat, starting
at a low initial level (3.5%), with a very low
decreasing (-0.006575) and increasing (-0.000093)
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Cismaş T. et. al./Scientific Papers: Animal Sciences and Biotechnologies, 2012, 45 (2)
Protein percentage (%)
rates, to and from a high nadir (3.4%) reached
early in lactation (71 days in milk).
Figure 8 show the lactation curves for milk lactose
percentage according to the parity of cows. Even
though the lactation curve parameters were a little
different, cows in lactation 1 and lactation 3+
showed similar shapes of the lactation curves for
lactose percentage. The initial starting point was
higher in lactation 3+ than in lactation 1 (4.8% vs.
4.6%, respectively), and both groups reached a
similar peak lactose percentage (4.9% and 4.8%,
respectively).
5
4,8
4,6
4,4
4,2
4
3,8
3,6
3,4
3,2
3
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Lactation 1
Lactation 2
Lactation 3+
Lactose percentage (%)
Figure 7. The shape of the lactation curve for protein percentage according to the parity
in Romanian Black and White cows
5,8
5,6
5,4
5,2
5
4,8
4,6
4,4
1
20
40
60
80 100 120 140 160 180 200 220 240 260 280 300
Days in milk
Lactation 1
Lactation 2
Lactation 3+
Figure 8. The shape of the lactation curve for lactose percentage according to the parity
in Romanian Black and White cows
A different shape and lactation curve parameters
were obtained for the second lactation cows.
These cows showed a significant higher initial
lactose percentage (5.2%), with rapid increasing
rate (0.021569) to a very high peak (5.7%),
reached at 157 days in milk, and then a rapid
decrease (0.000138) until the end of lactation.
These patterns make the curve of the second
lactation cows to be steeper than those of other
cows.
Similar results were obtained in previous works on
the shape of the lactation curve carried on
Holstein and Romanian Spotted breeds [17-19].
4. Conclusions
Based of our results we can state that the farm
management had a significant effect on the shape
of the lactation curve for milk yield, as well as for
299
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lactose).
There was a significant influence of the parity of
cows on the shape of the lactation curve for milk
yield, fat percentage, protein percentage and
lactose percentage.
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